Update: Today the Prop 8 case (Perry) is being argued before the Supreme Court and tomorrow the ACLU will be there challenging the constitutionality of the Defense of Marriage Act on behalf of Edie Windsor.

This is it – the Supreme Court marriage moment that the ACLU has been working towards for years. The Court announced today that it has granted review of the constitutionality of the Defense of Marriage Act in Edie Windsor’s case. The Court also took review of California’s Prop 8, so the full range of marriage issues will now be before the high court. These cases are poised not just to take down DOMA and Prop 8, but to be the next building blocks for LGBT equality more broadly.

The Windsor and Perry rulings, expected in June 2013, will be a watershed moment if our side wins either one.

Here’s why these cases are so important:

Ending explicit federal discrimination. DOMA requires the federal government to discriminate against married same-sex couples by treating them as legal strangers for purposes of all federal statutes and programs. There are approximately 120,000 married same-sex couples in the U.S. today, and DOMA treats all of them as single in each of the 1,100+ places in the federal code where being married makes a difference – from eligibility for family medical leave, to social security survivor’s benefits, to access to health care for a spouse. It’s the last explicit federal declaration that gay people are inferior, which is reason enough to get rid of it.

Heightened scrutiny in the balance. The Windsor ruling from the federal appeals court announced an important new protection for LGB people – “heightened scrutiny” by the courts. Under this standard, courts will presume that anti-gay discrimination by the government is unconstitutional and will require the government to have a good explanation for why it needs to treat us badly. Courts have usually applied a much less rigorous standard that often allows the government to discriminate against lesbians and gay men. While DOMA and Prop 8 should fail under any standard, if the Supreme Court adopts the heightened scrutiny standard, it would help eliminate anti-gay discrimination in many different contexts, from the workplace, to state parenting laws, to public schools across the country.

Showing the country that discrimination in marriage is wrong. Both Windsor and Perry make profound contributions to the public’s understanding of the freedom to marry. Edie’s story resonates because her relationship with Thea exemplifies what many people think marriage is all about – making a commitment to another person and sticking with it through difficult times. When two people make the commitment that’s at the heart of marriage, it’s profoundly unfair for the government to treat them as though they’re not a family. The evidence presented at the Prop 8 trial helped the country see how baseless are the many anti-gay stereotypes that are at the core of our opponents’ arguments. And having prominent conservatives like Ted Olson champion this cause gets a big chunk of America to take another look. Once they do, many realize they don’t really have a problem with same-sex couples tying the knot.

The two cases both involve marriage for gay couples, but they actually present quite distinct issues. Edie Windsor is already married – she just wants to stop the federal government from treating her marriage different from everyone else’s marriages. The plaintiffs in the Prop 8 case, on the other hand, want to get married. Their case presents the marriage issue to the Court full-on – Does California’s ban on marriage for same-sex couples violate the federal constitution? Our side could get a big win – marriage in all 50 states – or we could get a smaller win – marriage in California. Either win would be spectacular progress for our movement. I’m betting that the smaller win is more likely, but public opinion on this issue is changing so quickly that it’s becoming hard to predict what the Court will do in the end. The ACLU has filed supportive briefs in Perry all along, and we’ve been working for decades – in courts, in legislatures, in ballot campaigns, and with the public – to help get the country, and the court, ready for this moment.

As the Court moves forward, let’s take a look back at Edie’s story.

Edie Windsor and Thea Spyer’s relationship is destined to be a classic among love affairs: The two New Yorkers became a couple in 1965 and had the courage to get engaged in 1967, when marriage for same-sex couples was just a fantasy. In 1977, Thea was diagnosed with progressive multiple sclerosis, which gradually paralyzed her and ultimately left her unable to walk. Edie and Thea dealt together with the challenges of M.S. for the next 30-plus years.

The couple waited for years to be able to marry, and finally did so in 2007. In 2009, after 44 years together, Thea died.

Naturally Thea left her possessions, including the apartment they had shared for decades, to Edie. But while New York considered Edie and Thea married, DOMA required the federal government to treat them as legal strangers. So Edie was socked with a $363,000 federal estate tax bill that would have been $0 if she had been a straight widow. If you haven’t seen the video about Edie, take a look, it’s quite moving.

Heartbroken at the injustice, Edie challenged the constitutionality of DOMA. Two lower federal courts have struck down DOMA in her case, and now the Supreme Court will have the final word.

We’re headed for another marriage moment in just six months. Edie’s case will be a central part of that moment, and hers has all the right stuff – a compelling story, a perfect plaintiff, a top-notch legal team, and support from people across the country and around the globe. Importantly, Edie’s bravery and the strength of her love could change the reality for tens of thousands of same-sex couples.

We could not do this work alone, many thanks to our wonderful co-counsel in Edie’s case at Paul, Weiss, Rifkind, Wharton & Garrison LLP and the Stanford Law School Supreme Court Litigation Clinic.